HYOSUNG 2010 ST7 Service Manual page 264

Complaint
Engine runs poorly
in high speed
range.
Symptom and possible causes
Defective engine internal / electrical parts
1. Weakened valve springs.
2. Worn camshafts.
3. Valve timing out of adjustment.
4. Too narrow spark plug gaps.
5. Ignition not advanced sufficiently due to poorly working timing
advance circuit.
6. Defective ignition coils.
7. Defective pick-up coil.
8. Defective ECU.
9. Clogged fuel hose, resulting in inadequate fuel supply to injector.
10. Defective fuel pump.
11. Defective TP sensor.
12. Defective SAV solenoid.
13. Clogged air cleaner element.
Defective air flow system
1. Clogged air cleaner element.
2. Defective throttle valve.
3. Sucking air from throttle body joint.
4. Defective ECU.
Defective control circuit or sensor
1. Low fuel pressure.
2. Defective TP sensor.
3. Defective IAT sensor.
4. Defective pick-up coil.
5. Defective IAP sensor.
6. Defective ECU.
7. Defective SAV solenoid.
SERVICING INFORMATION 9-8
Remedy
Replace.
Replace.
Adjust.
Adjust.
Replace ECU.
Replace.
Replace.
Replace.
Clean and prime.
Replace.
Replace.
Replace.
Clean.
Clean or replace.
Adjust or replace.
Repair or replace.
Replace.
Repair or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.